Wild lettuce, also called bitter lettuce, is an annual and sometimes biennial herb that is original to Europe. Despite the name, the plant is not a vegetable but a member of the aster family, although the young, tender leaves are still harvested as a salad green in its native region.
Historically, wild lettuce has been used topically and internally. The plant produces a milky latex sap that hardens with contact with air. The leaf also contains a number of naturally occurring flavonoids.